Compressor installation



Sept. 23 192.

B. GRAEMIGER COMPRESSOR INSTALLATION Filed April 6', 1923 Patented Sept. 23, 1924.

UNITED STATES PATENT iOFFICE.

BENJAMIN GRAEMIGER, OF ZURICH,

SWITZERLAND, ASSIGNOR 'ro mu AKTIEN- 'GESELLSCHAFT DER MASCHIINENFABRIKEN ESCHECR ,WYSS & CIE, OF ZURICH,

SWITZERLAND.

COMPRESSOR INSTALLATION.

Application filed April 6, 1923. Serial No. 689,331.

To all whom it may concern: Be it known that I, BENJAMIN GRAEMIGER, a citizen of the Republic of Switzerland,

residing at Zurich, Switzerland, have in-' vented certain new and useful Improvements in Compressor Installations, of which the following is a specification, reference being had therein to the accompanying drawlugs.

The subject matter of the present invention is a compressor installation, comprising at least one main compressor and at least one additional compressor adapted to Work in work with adischarge pressure of, forv instance, 0.8 .atmospheres above atmospheric. In some cases (hanging of the'charge) however, a great increase in the pressure up to double the normal' pressure is required, whereby the quantity of air may decrease to a large extent; This manner of working, however, occurs comparatively seldom, so that it is justified .to take care that above all the normal working of such installations is as eflicient as possible. With compressors running at a constant speed (electromotor driven compressors) an, increase in pressure above the normal pressure cannot be obtained, unless the compressor is so 'constructed that it yields a low efficiency. at normal working. But also with installations adapted-to run at variable speed (turbine driven compressors) turbine and compressor yield a low efliciency at normal working if the compressor is so designed as to be able to discharge periodically at a pressure that is-greater than the normal pres-' sure.

In order to respond to the above men-. tioned requirements without having to put up with the drawbacks referred to, the additional compressor of an installation of the aforementioned type working in series with the main compressor is driven according to the present invention by a prime mover in which expands that part of the mediumdeliveredby the main compressor which does not enter into the additional compressor. The main compressor of such an installation may be so designed as to give the most favourable results at normal working. Likewise the engine driving the main compressor may be'built to yield the highest efficiency at normal working, The engine driving the additional compressor is simple and cheap. The work is, after all, performed by the well equipped and normally loaded engine driving the main compressor.

The additional compressor may be designed as a centrifugal compressor or as a, plston compressor.

In the first case the prlmemover driving the additional compressor is preferably a turbine and in the second case a piston engine.

constructional examples of the subject matter of the present invention are illustrated on the accompanying drawings, in which: 7 I

a first constructional example.

Fig. 2 shows a diagram illustrating the manner in which an installation according to the present invention operates.

Fig. 3 shows part of the construction of an additional compressor and of the power engine driving the former.

Figs. 4 and 5 show diagrammatically a second and a third constructional example respectively.

The installation illustrated in Fig. 1 comprises a centrifugal compressor acting as main compressor 1, which is driven by a power engine 2 of any suitable type. The medium sucked by the compressor 1 through the conduit 3 may be delivered into'a con Fig. 1 shows in a diagrammatic manner duit 4 in which a valve 5 is provided. 6 I

denotesan additionaheompressordriven by a .power engine 7. To the ressure conduit 4 a conduit 8 is connecte which divides itself at its one end into two branches 9, 10 of which the branch 9 may be used forsupplying medium delivered by the compressor 1 to the power engine 7 and the. branch 10 is adapted to supply that medium to the additional compressor 6. The connection between the conduits 4 and 8 is controlled by a valve -11. Themotive fluid supplied to the power engine 7 is dischar ed from the latter through a conduit 12. The medium, the pressure of which hasbeen raised in the additional compressor 6 is discharged into a conduit 13, the connection between* the latter and the conduit 4 being controlled by a valve 14.

During the normal working the valves 11 and 1'4-are cl sed, whilst the valve 5 is open. The main compressor 1 delivers then into the conduit 4 through which the compressed medium is supplied to the consuming place or laces.

en an increase in the pressure is re quired, the valve 5 is closed and the valves 11 and-14 are opened. The main compressor "1 discharges now into the conduit 8 which distributes the medium between the power engine 7 and 'the additional compressor 6. The latter is now connected in series with the main compressor.. The pressure of that part of the medium delivered by the main compressor -1 and passing throu h the additional compressor 6 is increas to the required height. The manner of working will be understood from the diagram illustrated in Fig. 2, in which volumepressure diagram 11. shows the characteristic of the main com- 8355501 running at the constant speed 11.

e steep curve a shows the combined working of the main compressor and the additional compressor. This curve is obtained by superpcsing the volume-pressurecharacteristics of the main compressor and of the additional compressor and by taking into account theoutput obtained from the medium expanding in the driving. engine for the additional compressor, (in which case the additional compressor is also a centrifugal compressor and the respective driving en ine is a turbine).

' 0 each po nt of the steep curve a a determined point of the curve 11. corresponds. If, for example, the point Q 42 corresponds to the maximum pressure required, theparts of the installation may be so chosen that to that point the point Q 12, of the main compressor corresponds whereb this point representsthe normal load 0 the main compressor. In order to obtain a quantitytll delivered at the required maximum pressure that is as large as possible, the correspondmg point Q p may be shifted into the overload range of the main compressor, whereby the capacity of thedriving engine to be'able' to work even when overloaded is made use of. This is the more advisable as generally the maximum pressure and thereby the overload is only required during a comparatively short time. If the engine driving the additional comlplressor admits a variation of its speed, the tter may be so increased beyond the normal speed in order to obtain the re quired maximum pressure that the service conditions for the point which corresponds to normalload are not materially prejudiced. In this case the characteristic n in the place of consumption.

As is shown inFig. 1, the part of the conduit 4 between the centrifugal compressor 1 and the valve 5 may be provided with a blow off valve 15. 'A blow off valve 16 may further be inserted in the conduit 13 between the additional compressor 6 and the valve 14.

With the constructional example illustrated in Fig.3 the additional compressor 6 is constructed as a centrifugal compressor and the power engine 7 driving the latter is constructed as anair turbine. The compressor and the turbine are provided with one inlet branch 17 common to both. The delivery branch 18 of the additional compressor 6 is arranged on one side and the discharge branch 19 of the air turbine 7 is arranged on the other side of the unit 6, 7 which is enclosed in one casing.

Two or more main compressors constructed as centrifu al compressorsmay be arranged to wor into one pressure conduit common to both in case an absolute reliability in the working of the installation is required as is articularly the case with compressor insta lations for blast furnaces. In

Fig. 4 a second main compressor 20 is indicated, which is adapted to Work into the same pressure conduit 4 as the main compressor 1 and to which the same additional compressor 6 appertains as'to the main compressor 1. In this case separate valves21, 22have to beprovided which permit of disconnecting the centrifugal compressor 1 or the centrifugal compressor 20 respectively from the pressure conduit 4 when the respective compressor is not operative. Assuming, for instance, the centrifugal oompremor 1 to be out of order and a higher pressure than the normal pressure to be required, then the valve 21 is closed and the valve 22 is opened. The valve 5 is closed and the valves 11 and 14 are opened, the compressor 6 works now in series with the compressor 20. If, on the other hand, normal pressure has to be produced and the centrifugal compressor 1 is shut down, only the valves 5 and 22 are opened and the valves 21, 11 and 14 are closed.

Between the valve 21 and the prewure conduit 4 a blow 01! valve 30 may be arranged and between the valve 22 and the peressure conduit 4 a blow ofi valve 23 may inserted.

As is shown in Fig. 5, the medium deliv- Fig. 2eorresp0udstothe highest permissible ered by the main compressor 1, may be prime movers driving the additional compressors are preferably also piston engines.

I claim:

1. A compressor installation, comprising in combination, at least one main compressor, an additional compressor adapted to work in series with said main compressor for the purpose of obtaining a higher pressure, and a driving engine for said additional compressor driven by that portion of the medium compressed in the main compressor which does not enter the additional compressor when working in series with-the main compressor.

2. A compressor installation comprising in combination, at least one main compressor, an additional compressor, means interposed between said compressors and adapted to conduct the compressed medium so that the additional compressor may work in series with the main compressor, and a driving engine for said additional compressor connected up to said conducting means so that the portion of the medium compressed in the main compressor which does not enter the additional compressor expands in said driving engine.

3. A compressor installation comprising in combination, at least .one main compressor, an additional compressor of the centrifugal type, means interposed between said compressors'and adapted to conduct the compressed medium so that the additional compressor may work in series with the main compressor, and a driving engine of the turbine type for the additional compre'ssor connected up to said conducting means so that the portion of the medium compressed in the main compressor which does not enter the. additional compressor expands in said driving engine.

4; A compressor installation comprising in combination, at least one main compressor, 'an additional compressor, means interposed between said compressors and adapted to conduct a portion of the medium.

compressed by the main compressor to said additional compressor so that the latter may work in series with the former, a cool.- ing device interposed in said conducting means, a driving engine for said additional compressor, and means adapted to conduct that portion of the medium compressed by the main compressor which is not dealt with in the additional compressor to said driving engine.

5. A compressor installation comprising in combination, a main compressor, an additional compressor, means interposed be tween said compressors and adapted to conduct a portion of the medium compressed by the main compressor to said additional compressor so that the latter may work in series with the former, a driving engine for said additional compressor, means adapted to conduct that portion of the medium'compressed by the main compressor which is not dealt with in the additional compressor to said driving engine, and a heating device interposed in said conducting means.

6. A compressor installation having at least one main compressor, in combination with 'a compressor in series therewith and an engine driven by medium compressed by said main compressor, heating means between said engine and main compressor and cooling means interposed between the two compressors.

7.- A compressor installation having at least one main compressor, in combination with an additional compressor receiving compressed medium from said main compressor, cooling means interposed between the compressors, and an engine for driving said additional compressor driven by compressed medium from said main compressor.

8. A compressor installation having at least one main compressor, in combination with an additional compressor. receiving compressed medium from said main compressor, cooling means for the medium delivered to said additional compressor, an engine for driving said additional compressor operated by medium from said main compressor and heating means to heat the drivin medium received by said engine.

n testimony whereof I affix my signature.

BENJAMIN GRAEMIGER. 

